1. Field of Invention
The present invention relates to a seat reclining apparatus.
2. Description of Related Art
Japanese Patent Laid-open Print No. Sho58-38511 published on Mar. 7, 1983 without examination discloses a seat reclining apparatus which includes a lower arm for attaching or fixing a seat-cushion, an upper arm for attaching or fixing a seat-back, a shaft pivotally attaching the upper arm to the lower arm, and a locking mechanism having a combination pawl and ratchet disposed between the lower arm and the upper arm. The pawl is positioned between a pair of spaced walls which are provided at the lower arm in order to oppose the ratchet. The meshing engagement of the pawl with the ratchet prevents the seat-back from rotating relative to the seat-cushion. When the meshing engagement between the pawl and the ratchet is released by moving the pawl away from the ratchet, the seat-back becomes rotatable relative to the seat- cushion. In order to facilitate a more or less smooth movement of the ratchet along the walls, a clearance is provided between the ratchet and each of the walls.
In the foregoing structure, in order to ensure that the meshing engagement between the pawl and ratchet is maintained even when a large force or load is applied to the seat-back in the direction of the rotation thereof relative to the seat-cushion, the clearance should be set as small as possible. However, the establishment of such a minimum clearance is difficult.